It is important that computer data storage systems can reliably maintain data stored in a disk drive in case of a particular memory failure or error. One commercially available technique for increasing disk drive reliability relies upon redundant data storage on disks such as “Redundant Array of Inexpensive Disks” (RAID) systems. Raid systems are currently used in many computer systems that demand improved reliability for data storage while utilizing relatively inexpensive memory disks. For example, banking and secure transactions over the Internet often rely upon RAID systems.
Certain levels of RAID involve the use of mirror disks, in which data is copied from among different disks. Today, changing such mirror-related configurations of RAID arrays has the disk volume go off-line. It would therefore be desirable to provide a mechanism to improve the reliability and reduce the down-time of RAID systems that result from reconfiguring of the disk drives.